Global cerebral blood flow decreases during pain.
Positron emission tomography studies have identified a common set of brain regions activated by pain. No studies, however, have quantitatively examined pain-induced CBF changes. To better characterize CBF during pain, 14 subjects received positron emission tomography scans during rest, during capsaicin-evoked pain (250 micrograms, intradermal injection), and during innocuous vibration. Using the H215O intravenous bolus method with arterial blood sampling, global CBF changes were assessed quantitatively. Painful stimulation produced a 22.8% decrease in global CBF from resting levels (P < 0.0005). This decrease was not accounted for by arterial PCO2 or heart rate changes. Although the exact mechanism remains to be determined, this pain-induced global decrease represents a previously unidentified response of CBF.
Coghill
R C
RC
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, Bethesda, Maryland, USA.
Sang
C N
CN
Berman
K F
KF
Bennett
G J
GJ
Iadarola
M J
MJ
D000328:Adult; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply*; D002211:Capsaicin; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010146:Pain / Q000503:physiopathology*; D014055:Tomography, Emission-Computed; D014732:Vibration
D002245:Carbon Dioxide; D002211:Capsaicin; D010100:Oxygen